1. Field of the Invention
The present invention generally relates to mobile communication networks.
In a general way, mobile communication networks are subject to standardisation; therefore a more detailed description of such networks can be found in the corresponding standards, published by the corresponding standardisation bodies, such as for example 3GPP (3rd Generation Partnership Project”).
2. Description of the Prior Art
It is simply recalled that, as specified in particular in Technical Specification 3GPP TS 23.002, the architecture of such networks is logically divided into an Access Network (AN) and a Core Network (CN), and the architecture of the Core Network is logically divided into different domains and subsystems, including a Circuit Switched (CS) domain, a Packet Switched (PS) domain, and an IP (Internet Protocol) Multimedia Subsystem (IMS).
IMS is defined in particular in Technical Specification 3GPP TS 23.228 published by the 3GPP. As defined in this Technical Specification an architecture for the support of IP multimedia services is divided into an IP-Connectivity Access Network (IP-CAN), and an IP Multimedia CN Subsystem (IMS). An example of access technology for the support of IMS services corresponds to the GPRS CN with a RAN corresponding to GERAN (or more generally a Radio Access Technology of 2.5 Generation or 2.5G) and/or UTRAN (or more generally a Radio Access Technology of 3rd Generation or 3G). Other examples of access technologies for the support of IMS services are of course possible, such as for example WLAN (Wireless Local Area Network.
It is also recalled that, as specified in particular in Technical Specification 3GPP TS 23.002, the CN includes a Home Subscriber Server (HSS) which is a database entity containing the subscription-related information to support the call control and session management entities of the different domains and subsystems of the operator. FIG. 1 taken back from 3GPP TS 23.002 recalls the interfaces for communication between the different functionalities of the HSS and the different entities of the different domains and subsystems of the Core Network. The HSS comprises a IMS functionality providing support to IMS subsystem entities and holding subscription data for said support, and a HLR (Home Location Register) functionality providing support to CS domain entities, PS domain entities, and entities called 3GPP AAA Server required for interworking with WLAN, and holding subscription data for said support. The HSS can provide data repository for different IMS Application Servers. As also recalled in FIG. 1, IMS Application Server retrieve subscription data relative to the Application over an interface called “Sh” interface, to support Application Services in the IMS subsystem.